Use lazy copy to patch resources to ensure multiple modifications are applied to the base resource

[nikola-jokic]

Based on #4575

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Pull request overview

This PR modernizes how the controllers detect/propagate desired-state changes and how they compute patches, replacing integrity-hash annotations with explicit revision/generation tracking and adding a shared in-memory resource cache to avoid rebuilding identical desired objects.

Changes:

• Introduces a ResourceCache used by ResourceBuilder to reuse desired objects based on a main-object key plus dependency refs.
• Replaces integrity-hash–based update detection with ActionableRevision/AppliedActionableRevision for EphemeralRunnerSet and ObservedGeneration for AutoscalingRunnerSet (and updates CRDs accordingly).
• Refactors patch flows to use a lazy DeepCopy helper (once) so multiple in-place mutations can be safely applied before client.MergeFrom(...).

Reviewed changes

Copilot reviewed 25 out of 25 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
main.go	Instantiates and wires a shared ResourceCache into ResourceBuilder.
controllers/actions.github.com/utils.go	Adds once lazy-copy helper used to build correct MergeFrom patches.
controllers/actions.github.com/utils_test.go	Moves test-only random string helper into tests.
controllers/actions.github.com/resourcecache.go	Adds typed resource cache with dependency-key tracking and eviction by owner UID.
controllers/actions.github.com/resourcecache_test.go	Adds unit tests for cache semantics (dependency ordering, deletion, invalid inputs).
controllers/actions.github.com/resourcebuilder.go	Uses cache for desired-object reuse; removes integrity-hash annotations; refactors label/annotation merging.
controllers/actions.github.com/resourcebuilder_test.go	Updates tests for removed integrity-hash annotation; adds merge-map tests and cache expectations.
controllers/actions.github.com/helpers.go	Adds helper predicates for actionable revision and pod recreation decisions.
controllers/actions.github.com/ephemeralrunnerset_controller.go	Switches to actionable revision + status patching with conflict retries; refactors patching with lazy copies.
controllers/actions.github.com/ephemeralrunnerset_controller_test.go	Updates/extends integration tests for cache cleanup and actionable revision behavior.
controllers/actions.github.com/ephemeralrunner_controller.go	Refactors finalizer patching to use lazy-copy pattern; deletes cached entries on deletion.
controllers/actions.github.com/ephemeralrunner_controller_test.go	Extends tests to assert cache cleanup on runner deletion.
controllers/actions.github.com/autoscalingrunnerset_controller.go	Uses observed generation for Pending detection; switches spec-change handling to actionable revision; refactors patch logic.
controllers/actions.github.com/autoscalingrunnerset_controller_test.go	Updates tests to assert observed generation and actionable revision behavior; adds cache assertions.
controllers/actions.github.com/autoscalinglistener_controller.go	Refactors patching of dependent resources using lazy copies; updates pod recreation decision logic.
controllers/actions.github.com/autoscalinglistener_controller_test.go	Extends tests to assert resources are cached and evicted appropriately.
config/crd/bases/actions.github.com_ephemeralrunnersets.yaml	Adds actionableRevision, appliedActionableRevision, finishedRunnerCleanupPatchID schema fields.
config/crd/bases/actions.github.com_autoscalingrunnersets.yaml	Adds observedGeneration to status schema.
charts/gha-runner-scale-set-controller/crds/actions.github.com_ephemeralrunnersets.yaml	Mirrors ERS CRD schema additions into chart CRDs.
charts/gha-runner-scale-set-controller/crds/actions.github.com_autoscalingrunnersets.yaml	Mirrors ARS CRD schema additions into chart CRDs.
charts/gha-runner-scale-set-controller-experimental/crds/actions.github.com_ephemeralrunnersets.yaml	Mirrors ERS CRD schema additions into experimental chart CRDs.
charts/gha-runner-scale-set-controller-experimental/crds/actions.github.com_autoscalingrunnersets.yaml	Mirrors ARS CRD schema additions into experimental chart CRDs.
apis/actions.github.com/v1alpha1/version.go	Minor condition reordering in version allowance check.
apis/actions.github.com/v1alpha1/ephemeralrunnerset_types.go	Adds ActionableRevision spec field and applied/cleanup status fields.
apis/actions.github.com/v1alpha1/autoscalingrunnerset_types.go	Adds ObservedGeneration to status.

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